Sweetpotato plant named ‘NC04-0531’

ABSTRACT

Ipomoea batatas  ‘NC04-0531’ is an orange fleshed, smooth skinned, dark rose-colored, table stock sweetpotato. ‘NC04-0531’ has good insect resistance. It has an upright, compact canopy that helps to suppress weeds within a row and is slower to trail across rows allowing for a longer period of cultivation with weed control. It is a long season variety to size for optimal production of No. 1 sized roots. Size and shape uniformity of ‘NC04-0531’ are very good. The flavor of the baked storage roots of ‘NC04-0531’ has been judged to be very good by standardized and informal taste panels. Because of its insect resistance and plant canopy characteristics, ‘NC04-0531’ is seen as a good option for organic production.

Latin name of the genus and species: The Latin name of the novel plantcultivar disclosed herein is Ipomoea batatas (L.) Lam.

Variety denomination: This new and distinct sweetpotato cultivar ofIpomoea batatas (L.) Lam. has been given the denomination ‘NC04-0531’.

BACKGROUND OF THE INVENTION

Ipomoea batatas is a member of the morning glory family Convolvulaceae.This species is grown worldwide, and it exhibits a wide range of plantforms and colors. Grown by farmers worldwide, the cultivated members ofIpomoea batatas are commonly produced for consumption of theirnutritious, enlarged storage roots. This contrasts with potatoes(Solanum tuberosum), which produce an edible tuber derived from anunderground stem, which is similar in structure to the above groundstems.

Presently, there are two dominant sweetpotato cultivars produced in theUnited States, ‘Covington’ (U.S. Plant Pat. No. 18,516) and ‘Beauregard’(unpatented). ‘NC04-0531’ provides an improvement over ‘Covington’ and‘Beauregard’ in that it has increased resistance to insect damage, and acanopy that is more upright and has a less trailing plant habit allowingfor a longer mechanical cultivation period for weed control. ‘NC04-0531’provides an improvement over ‘Beauregard’ in consistency of storage rootshape attributes.

Lineage. ‘NC04-0531’ originated from bulked botanical seed harvestedfrom the open pollinated female parent ‘Ruddy’ (not patented) in the2003 Elite polycross nursery. The 2003 Elite breeding nursery wasplanted in Clayton, Johnson County, N.C. The 15 genotypes present in theElite nursery were randomly mated during the course of a five-monthflowering period in which seed was harvested and bulked per femaleparent from the 15 genotypes present in the nursery; therefore, the maleparent of ‘NC04-0531’ is unknown. Two patented male parents (‘L96-117’(U.S. Plant Pat. No. 15,038) and ‘Bienville’ (U.S. Plant Pat. No.15,380)) were in the nursery and these represent potential pollensources.

Seedlings from the 2003 Elite polycross nursery were planted in Clinton,N.C. greenhouses in March of 2004. A single cutting was taken from eachseedling and planted in the field on May 22^(nd) in Kinston N.C. and‘NC04-0531’ was selected as a “single plant selection” on September13^(th). This “single plant selection” included all of the storage rootsderived from the single plant cutting planted on May 23^(rd), typically2-15 storage roots, with 2-10 storage roots being saved over the winterin our storage facility in Clinton, N.C. for propagation the next yearvia vegetive propagation in the same location.

Asexual Reproduction. The first asexual reproduction of ‘NC04-0531’occurred in Clinton, N.C. ‘NC04-0531’ has been propagated as vegetativestem cuttings and/or storage root derived stem cuttings derived fromadventitious sprouts emanating from its storage roots since its originalselection in September of 2004. After further cycles of selection forhorticultural traits and disease screenings, ‘NC04-0531’ was subjectedto meristem tip culture and subsequent tissue culture maintenance toeliminate viruses and pathogens via meristem tip culture. Thecharacteristics disclosed herein for ‘NC04-0531’ have remained stableand the plant has reproduced true to type through successive generationsof asexual propagation.

SUMMARY OF THE INVENTION

‘NC04-0531’ is an orange-fleshed, smooth-skinned, dark rose-coloredtable stock sweetpotato. The storage roots of ‘NC04-0531’ tend to beelliptic and similar in length to ‘Covington’ but shorter than‘Beauregard’, and more uniform in size and shape than ‘Beauregard’. Oneof the desirable traits of ‘NC04-0531’ is that it produces moreconsistent storage root shapes than ‘Beauregard’, especially in soilswhere ‘Beauregard’ can be long and irregular. The length of the storageroots of ‘NC04-0531’ are similar to ‘Covington’ and shorter than‘Beauregard’. ‘NC04-0531’ produces a similar percentage of No. 1 storageroots to ‘Covington’. ‘NC04-0531’ is a later maturity clone and does notyield as high as ‘Covington’ and ‘Beauregard’, when these three clonesare harvested at the same time. Plants from bedded storage roots of‘NC04-0531’ are ready 10 days to two weeks before ‘Covington’.‘NC04-0531’ has been rated more resistant to insect damage than‘Covington’ and ‘Beauregard’, and has a compact, upright growth habitthat allows for a longer cultivation period than ‘Covington’ and‘Beauregard’ without damaging the vines. The insect resistance andlonger cultivation period make ‘NC04-0531’ an attractive option fororganic producers. The dry matter content is higher for ‘NC04-0531’ thanfor ‘Covington’ and ‘Beauregard’. The flavor of baked storage roots of‘NC04-0531’ have been judged to be very good by standardized andinformal taste panels. ‘NC04-0531’ typically scores as well as or betterthan ‘Covington’ and ‘Beauregard’ for baking quality. The female parentline, ‘Ruddy’, was no longer propagated at the time that ‘NC04-0531’ wasbeing evaluated. So, with the exception of insect resistance, ‘Ruddy’was not used for comparison. ‘Ruddy’ is not grown commercially.

BRIEF DESCRIPTION OF THE DRAWINGS

The photographs in the drawings were made using conventional techniquesand show the colors as true as reasonably possible by conventionalphotography. Colors in the photographs may differ slightly from thecolor values cited in the detailed botanical description, whichaccurately describe the colors of the new Ipomoea batatas.

FIG. 1 is a color photograph of the above ground plant canopy producedby the new cultivar ‘NC04-0531’ (left panel), ‘Covington’ (middle panel)and ‘Beauregard’ (right panel) 57 days after planting at in Kinston,N.C. in 2017.

FIGS. 2A-2C are color photographs of typical mature leaves of‘NC04-0531’ (FIG. 2A), ‘Covington’ (FIG. 2B), and ‘Beauregard’ (FIG. 2C)57 days after planting in Kinston, N.C. in 2017.

FIGS. 3A-3C are color photographs showing typical vines and the varietyof leaves of ‘NC04-0531’ (FIG. 3A), ‘Covington’ (FIG. 3B), and‘Beauregard’ (FIG. 3C) 57 days after planting in Kinston, N.C. in 2017.

FIG. 4 is a color photograph showing typical storage roots produced by‘NC04-0531’. The photographs were taken of storage roots that had beenstored in a sweetpotato storage facility for approximately three monthsafter harvest.

DETAILED BOTANICAL DESCRIPTION

The following is a detailed description of the botanical characteristicsof a new and distinct cultivar of Ipomoea batatas plant given thedesignation ‘NC04-0531’. All colors cited herein refer to The RoyalHorticulture Society Colour Chart designations (The Royal HorticulturalSociety, London, 1995, 4^(th) ed.) except where general terms ofordinary dictionary significance are used. Plant descriptions are basedon the standardized international sweetpotato descriptors establishedjointly by the International Potato Center (CIP), Lima, Peru; The AsianVegetable Research and Development Center (AVRDC), Taipei, Taiwan; andthe International Board for Plant Genetics Resources (IBPGR), Rome,Italy (CIP, AVRDC, IBPGR. 1991. Descriptors for Sweet Potato. Huaman,Z., editor. International Board for Plant Genetic Resources, Rome,Italy, 134pp.). Where dimensions, sizes, colors, and othercharacteristics are given, it is to be understood that suchcharacteristics are approximations or averages set forth as accuratelyas practicable.

The descriptions and measurements of plant canopy reported herein weredone on field grown plants 57 days after planting (DAP). The plants weregrown in Kinston, N.C. under common commercial sweetpotato productionpractices during June through October. ‘NC04-0531’ has not been observedunder all possible environmental conditions; therefore, the phenotypemay vary under different environmental conditions such as season,temperature, light intensity, day length, cultural conditions, and thelike, without however, any variance in the genotype.

The following discussion provides a description of the new Ipomoeabatatas ‘NC04-0531’ with ‘Beauregard’ and ‘Covington’ for comparison.

-   Classification:    -   -   Botanical name.—Ipomoea batatas (L.) Lam.        -   Common name.—Sweetpotato.        -   Variety name.—‘NC04-0531’.

Growth Conditions Whole-plant Canopy Structure. FIG. 1 is a colorphotograph of the canopy biomass produced by the new cultivar‘NC04-0531’ and contrasted with ‘Covington’ and ‘Beauregard’.Measurements were collected on field-grown plants at 57 DAP using 20measurements per trait and recorded as the mean. ‘NC04-0531’ averaged1.4 main vines and ‘Covington’ and ‘Beauregard’ each averaged 1.1 mainvines. Mean main vine lengths were 66, 179, and 136 cm for ‘NC04-0531’,‘Covington’, and ‘Beauregard’, respectively. The mean main vine stemdiameter at the base was 8.2, 8.1, and 8.4 mm (‘NC04-0531’, ‘Covington’,and ‘Beauregard’, respectively). At 50 cm from the base of the mainvine, the mean stem diameter was 6.2, 4.9, and 4.8 mm for ‘NC04-0531’,‘Covington’, and ‘Beauregard’, respectively. The average lateralbranches per main vine was 5.3 for ‘NC04-0531’, 4.5 for ‘Covington’, and5.9 for ‘Beauregard’. Stem color was green (N144B to 144B) for‘NC04-0531’, 145A for ‘Covington’, and 144B for ‘Beauregard’. The firstinternode length beginning at the apex between the first and secondfully expanded leaves was 30 mm for ‘NC04-0531’, 52 mm for ‘Covington’,and 56 mm for ‘Beauregard’. ‘NC04-0531’ appeared to have a denser canopyand greater ground cover for potential weed suppression ability withinthe rows when compared to ‘Covington’ and ‘Beauregard’.

Foliage. The leaves of ‘NC04-0531’ are alternate and simple instructure, and cordate to very slightly lobed in shape. (FIGS. 2A and3A). The leaves have a smooth texture and matte finish. Mature leafcolor for ‘NC04-0531’, ‘Covington’, and ‘Beauregard’ is green, between147A and 147B on the upper leaf surface and 147B on the lower surface.Young leaf color, upper and lower, displayed variation among the threecultivars; ‘NC04-0531’ was green between 146A to 146B, ‘Covington’ wasgreen 147B with secondary purple base (N79A), and ‘Beauregard’ was green147A with secondary purple (N79B), however slightly less purplepigmentation than ‘Covington’. Mean leaf length was 122 mm for‘NC04-0531’, 119 mm for ‘Covington’ and 114 mm for ‘Beauregard. Leafwidth was 145 mm for ‘NC04-0531’, 134 mm for ‘Covington’, and 119 mm for‘Beauregard’. All three cultivars have a purple spot (N79B) spot at thebase of the main rib. Petioles of ‘NC04-0531’ are green (144C) withpurple near leaf blade (N79A), and green (144B) for both ‘Covington’ and‘Beauregard’ with no secondary color. Mean petiole length and diametermeasured 205 mm and 5.8 mm for ‘NC04-0531’, 181 mm and 5 mm for‘Covington’, and 158 mm and 4.5 mm for ‘Beauregard’. Stem tipanthocyanin coloration of ‘NC04-0531’ is absent with sparse pubescence.

A typical inflorescence of ‘NC04-0531’ has two clusters of 6-10 flowersper peduncle. Peduncles are green (144A) averaging 12 cm long and about3.5 mm in diameter. Flowers are 3.5 to 4 cm long from the base of thecalyx, and the corolla is 4 to 4.5 cm wide. Petals are fused to form apentagonal limb with smooth edges. The inner throat color is purple(N81A) with a white inner and outer limb. Upper and lower flower textureis smooth. The five sepals making up the calyx were elliptic with anacute tip. The three inner sepals were 12 mm long and 5.4 mm wide whilethe outer two sepals were shorter, 10.5 mm long and 3.3 mm wide. Allsepals were green (144A) with smooth edges. The pistil averages 16 mm inlength and are white and the stigma is slightly inserted. Anthers arewhite with the style being white with purple at the base (76A). Nofragrance is present.

Storage Roots. ‘NC04-0531’ produces orange fleshed (between 28B and29A), smooth skinned, storage roots that are generally elliptic. Theskin color of ‘NC04-0531’ is dark rose (178B to N181A) (FIG. 4), whichis typically darker and redder than ‘Covington’ when grown under similarconditions. One of the additional desirable attributes of ‘NC04-0531’ isthat it produces roots that are shorter than ‘Beauregard’ for soils andconditions where ‘Beauregard’ can be long. Roots of ‘NC04-0531’ aregenerally similar in length to ‘Covington’ and shorter in length to‘Beauregard’. Length to diameter ratios of storage roots in 26 trialsover seven years averaged 2.4, 2.6 and 2.0 for ‘NC04-0531’, ‘Beauregard’and ‘Covington’ respectively. Root number and size was measured for 11trials in 2017 and 2018 with ‘NC04-0531’ averaging 3.3 roots per plantwhile ‘Beauregard’ averaged 4.9 and ‘Covington’ 4.1 roots per plant.Mean length of the roots for ‘NC04-0531’ was 4.4 inches and mean width2.3 inches. For ‘Beauregard’, mean length of the roots was 5.0 incheswith a mean width of 2.4 inches, and for ‘Covington’ mean length of theroots for was 4.6 inches with a mean width of 2.4 inches. Carbohydrateprofiles and β carotene levels are similar to ‘Beauregard’ and‘Covington’, with all three being moist, sweet, orange-fleshed types(Table 1). Percent dry matter and starch content is slightly higher for‘NC04-0531’ than both ‘Beauregard’ and ‘Covington’, but not differentenough to change cooking quality. The flavor of the baked storage rootsof ‘NC04-0531’ have been judged to be very good by standardized andinformal taste panels comparing well with ‘Covington’.

TABLE 1 Carbohydrate, n-carotene and asparagine profiles of ‘NC04-0531’,‘Beauregard' and ‘Covington’ from the same trials averaged over 5 trialsin 2014, 6 in 2015, 4 in 2016 and 10 trials in 2017. Starch FructoseGlucose g/100 g g/100 g g/100 g % dry dry fresh fresh Cultivar matterweight weight weight 2014 ‘N004-0531’ 23.6 ± .6 53.2 ± 2.4 0.39 ± .030.50 ± .05 ‘Beauregard’ 19.3 ± .2 49.3 ± 0.9 0.77 ± .04 1.03 ± .06‘Covington’ 20.9 ± .7 42.2 ± 2.1 0.58 ± .06 0.75 ± .09 2015 ‘NC04-0531’23.8 ± .3 55.5 ± 1.5 0.35 ± .01 0.43 ± .02 ‘Beauregard’  18.5 ± 1.5 44.5± 4.0 0.70 ± .10 0.94 ± .14 ‘Covington’ 21.0 ± .8 44.8 ± 1.9 0.45 ± .060.56 ± .08 2016 ‘NC04-0531’ 23.3 ± .7 48.4 ± 3.0 0.36 ± .05 0.48 ± .10‘Beauregard’ 19.8 ± .6 47.9 ± 1.2 0.77 ± .07 1.01 ± .11 ‘Covington’ 21.4± .6 42.8 ± 3.5 0.41 ± .06 0.52 ± .10 2017 ‘NC04-0531’ 23.9 ± .4 53.0 ±1.1 0.37 ± .02 0.46 ± .03 ‘Beauregard’ 21.2 ± .4 53.0 ± 1.2 0.67 ± .040.88 ± .06 ‘Covington’ 22.4 ± .5 46.9 ± 1.6 0.41 ± .02 0.50 ± .02Sucrose Total sugars g/100 g g/100 g β-carotene Asparagine fresh freshmg/g dry mg/g Cultivar weight weight wt dry wt 2014 ‘N004-0531’ 2.22 ±.19 3.11 ± .27 0.46 ± .02 0.96 ± .20 ‘Beauregard’ 1.10 ± .06 2.89 ± .110.46 ± .01 1.20 ± .32 ‘Covington’ 2.63 ± .07 3.96 ± .19 0.55 ± .02 0.91± .15 2015 ‘NC04-0531’ 1.87 ± .11 2.65 ± .10 0.40 ± .01 1.33 ± .23‘Beauregard’ 0.89 ± .12 2.52 ± .25 0.41 ± .02 2.24 ± .39 ‘Covington’2.19 ± .11 3.20 ± .13 0.48 ± .02 1.68 ± .22 2016 ‘NC04-0531’ 2.30 ± .193.14 ± .30 0.46 ± .06 1.12 ± .19 ‘Beauregard’ 0.98 ± .09 2.76 ± .25 0.40± .02 1.26 ± .12 ‘Covington’ 2.68 ± .29 3.61 ± .41 0.51 ± .05 0.92 ± .222017 ‘NC04-0531’ 2.33 ± .08 3.17 ± .10 0.44 ± .03 1.04 ± .14‘Beauregard’ 1.20 ± .04 2.75 ± .10 0.40 ± .02 1.24 ± .17 ‘Covington’2.59 ± .13 3.50 ± .15 0.54 ± .02 0.91 ± .12 Values are based onpredictions using Near Infrared Reflectance Spectroscopy (NIRS)calibrations. Samples are measured 4-10 weeks after harvest. Values aremeans with standard errors.

Storage Root Yield. Yield comparisons of ‘NC04-0531’ are with‘Covington’ and ‘Beauregard’, the two major sweetpotato cultivars grownin the U.S. In the 30 replicated yield trials comparing ‘NC04-0531’,‘Beauregard’ and ‘Covington’, ‘NC04-0531’ averaged 85% of the totalmarketable yield (TMY) of ‘Beauregard’ and 81% the TMY of ‘Covington’(Table.2). While the yields in these trials were lower for ‘NC04-0531’,the timing for these trials were based on optimal sizing for No. 1 sizedroots for the check cultivars, ‘Beauregard’ and ‘Covington’. ‘NC04-0531’does not bulk as quickly as the check cultivars and would normally beleft to grow for 2-4 weeks longer to optimize production of No. 1 sizedroots. ‘Beauregard’ and ‘Covington’ are typically harvested between100-120 days after planting, while recommendations for ‘NC04-0531’ are115-140 days. Yields are closer to the ‘Beauregard’ and ‘Covington’ whenfollowing these guidelines, which guidelines are common for later sizingcultivars. Production of off shaped roots, which if severe would beculled, is similar to ‘Covington’ and less than ‘Beauregard’.

TABLE 2 Average performance of ‘NC04-0531’, ‘Covington’ G2* and B94-14G2* ‘Beauregard’ over 30 yield tests, 2007-2017. Size Distribution byNo. Marketable Class (% 1 Total Yield of total yield) 50 Yield % % No.Jum- lb Cultivar bu/A bu/A Beau Cov 1 Can bo Cull bu/ac ‘NC04-0531’ 698663 85 81 57 27 11 5 378 ‘Covington’ 909 850 108 58 16 20 6 493 G2‘Beauregard’ 965 842 102 47 14 26 13 396 G2-3 (B94-14) *G2 - Fieldgeneration designation of the planting materials used in the trials US#1's - Roots 2″ to 3½″ diameter, length of 3″ to 9″, must be well shapedand free of defects. Canners - Roots 1″ to 2″ diameter, 2″ to 7″ inlength. Jumbos - Roots that exceed the diameter, length and weightrequirements of the above two grades, but are of marketable quality.Percent US #1's - Calculated by dividing the weight of US #1's by thetotal marketable weight (Culls not included). Culls - Roots must be 1″or larger in diameter and so misshapen or unattractive that they couldnot fit as marketable roots in any of the above three grades.

Insect Resistance. ‘NC04-0531’ has good resistance to the WDS (wireworm,Diabrotica, Systena) complex of insects, which are the major causes ofinsect damage of sweetpotato in North Carolina, compared to the majorcultivars ‘Beauregard’ and ‘Covington’. The results of four replicatedfield insect screen trials are shown in Table 3. WDS resistance issimilar to slightly less than ‘Ruddy’ which is used as an insectresistant check and is the parent of ‘NC04-0531’. Sweetpotato fleabeetle (Chaetocnema confinis Crotch) and sweetpotato weevil (Cylasformicarius (F.) damage were too low in these trials to assessresistance.

TABLE 3 Insect resistance screens with ‘NC04-0531’, ‘Beauregard’,‘Covington’ and ‘Ruddy’ sweetpotatoes in four replicated trials. WDS¹SPFB² SPW³ Sweetpotato Uninjured severity damaged damaged genotyperoots, % index roots, % roots, % 2012 USDA-US Vegetable Lab Advancedtrial evaluation ‘Ruddy’^(b) 95 a .03 b 1.8 b 0 a ‘NC04-0531’ 69.5 b .25b 10.6 ab 2.1 a ‘Covington’ 38.8 c .69 a 7.4 ab 7.3 a ‘Beauregard’^(c)29 c .84 a 14.8 a 5.3 a 2012 USDA-US Vegetable Lab Insect trialevaluation ‘Ruddy’ 99.2 0.000 0.01 0 ‘NC04-0531’ 87.5 0.095 0.03 0.02‘Covington’ 73.4 0.255 0.02 0.01 ‘Beauregard’ 73.0 0.253 0.05 0 2011USDA-US Vegetable Lab Insect trial evaluation ‘Ruddy’ 87.3 0.120 0 0‘NC04-0531’ 85.7 0.105 0.03 0 ‘Covington’ 34.5 0.737 0.05 0.003‘Beauregard’ 21.1 1.155 0.02 0.003 2007 NCSU insect resistance trials‘NC04-0531’ 20.4 a 1.10 b 1.0 b NA ‘Covington’ 21.3 a 1.17 b 2.0 b NA‘Beauregard’ 7.3 b 1.74 a 12.6 a NA ¹Wireworm, Diabrofica, Systena (WDS)complex: severity index: 1 = 1-5 scars, 2 = 6-10 scars, 4_10 scars,averaged over all roots; maximum score = 4. ²Sweetpotato Flea beetle(SPFB) damage - Chaetocnema confinis Crotch ³Sweetpotato Weevil (SPW)damage - Cylas formicarius (F.) ‘Ruddy’ is the resistant check for WDS,‘Beauregard’ is the susceptible check. Means within columns followed bya common letter are not significantly different (P = 0.05, Fisher'sLeast Significant Difference).

Disease or Pest Resistance. Table 4 summarizes the results of diseaseevaluations of ‘NC04-0531’. Based on multiyear disease evaluations,‘NC04-0531’ is resistant to Fusarium wilt (Fusarium oxysporum Schlect.f. sp. batatas (Wollenw.) Snyd. & Hans.), Streptomyces soil rot(Streptomyces ipomoeae (Person & W. J. Martin) Waksman & Henrici) and tosouthern root knot nematode, Melodogyne incognita (Kofoid & White). TheFusarium resistance of ‘NC04-0531’ is similar to ‘Covington’, which isimportant since there is no cultural control.

TABLE 4 Disease screen results for ‘NC04-0531’, ‘Beauregard’ and‘Covington’ over five years for Southern root-knot nematode (Meloidogyneincognita) (Kofoid & White), fusarium wilt (Fusarium oxysporum Schlect.f sp. batatas (Wollenw.) Snyd. & Hans.), and Streptomyces soil rot(Streptomyces ipomoeae (Person & W. J. Martin) Waksman & Henrici) 20142009 2008 2007 2006 Average ‘NC04-0531’ Root-knot R HR R R MR R nematodeFusarium wilt R R R R HR R SSR - GH MS R R R — MR-R SSR - field R R R RR R ‘Covington’ Root-knot R R R R MR R nematode Fusarium wilt R R R R RR SSR - GH MR R R R R R SSR - field R R R R R R ‘Beauregard’ Root-knotHS HS HS S HS HS nematode Fusarium wilt MR MR R R R MR-R SSR - GH R R RR — R SSR - field R R R R R R Scale - HS - highly susceptible, S -susceptible, MS - moderately susceptible, MR - moderately resistant, R -resistant, HR - highly resistant

In Table 4, the root knot nematode rating is based on the number ofgalls on roots counted eight weeks after inoculation with 10,000 eggs ofM. incognita race 3 in plants established in four-inch pots. Gall countclasses: HR=0; R=1-3; MR=4-10; MS=11-30; S=31-100; HS=101+galls. 4 reps.The Fusarium wilt rating involves dipping fresh cut plants in a solutionof Fusarium oxysporum spores then rating for mortality and vasculartissue browning. 3 reps of five plants each are used. Streptomyces soilrot is screened in both the greenhouse and field. The greenhouse trialinvolves planting slips into media that is a mix of sand and vermiculitemedia on which the bacteria is raised. Rating on damage to fibrous rootsis done 8-10 weeks after planting. The field trial is in a field withhigh levels of SSR pressure. Plots are rated for both fibrous rootdamage, yield and storage root lesions

Long term storage. Sweetpotatoes from yield trials are stored and ratedfor the ability to last until the next crop season. They are rated on avisual pithiness scale from 0 to 4, where 0 has visible holes, to 4,where there is no visible pithiness, or they look like freshly harvestedroots. This rating system is used as an estimate of how well the rootshave lasted in storage. The sweetpotatoes are also rated for sprouting,another measure of long-term storage, which is also reflected in thepithiness score. ‘NC04-0531’ had an average pithiness score of 2.9averaged over 13 trials from 2012 to 2018. In the same years, thepithiness score for ‘Covington’ averaged 2.4 and 2.3 for ‘Beauregard’,both of these ratings are considered good for storage ability. So, wewould also consider ‘NC04-0531’ to be good. Sprouting for ‘NC04-0531’was minimal, similar to ‘Covington’ and ‘Beauregard’.

‘NC04-0531’ is a fairly prolific producer of latex, which when the rootsare broken off during harvest may exude from the root and run down theside of the sweetpotato. When the latex dries it turns black which isconsidered a visual defect. It does not come off in the packing process

Flood tolerance appears to be slightly less for ‘NC04-0531’ than‘Covington’ under wet conditions. ‘Covington’ is considered tolerant towet conditions, though any cultivar will be lost if submerged.‘NC04-0531’ will show a proliferation of lenticels under wet conditions.

We claim:
 1. A new and distinct cultivar of Ipomoea batatas plant named‘NC04-0531’, substantially as illustrated and described herein.